Final answer:
Nucleophilic substitution in haloalkanes occurs when a nucleophile attacks the carbon with the leaving group, usually leading to inversion of stereochemistry as the product forms.
This reaction is common with primary alkyl halides and may proceed via SN1 or SN2 mechanisms.
Step-by-step explanation:
Nucleophilic substitution in haloalkanes typically occurs in three steps. Initially, a nucleophile (N) attacks a carbon atom in the haloalkane, as a leaving group (often a halide) departs.
This process leads to the formation of an unstable transition state that quickly resolves into the final substituted product. In this reaction, the stereochemistry is commonly inverted as a result of the nucleophile attacking from the opposite side of the leaving group.
For example, in a laboratory setting, an O-methylation reaction can be demonstrated where an alcohol's oxygen atom acts as a nucleophile to displace the iodide in methyl iodide.
The iodide is a highly effective leaving group in this context. This type of mechanism is particularly typical for primary alkyl halides.
Additionally, while nucleophilic substitution can follow either the SN1 or SN2 mechanism, the choice between these pathways can affect both the reaction rate and the stereochemistry of the product.